Modified graphite and preparation method thereof, secondary battery, battery module, battery pack, and electrical device

Abstract

Graphite and a preparation method thereof, a secondary battery containing the modified graphite, a battery module, a battery pack, and an electrical device are provided. In particular, the modified graphite according to this disclosure includes a graphite moiety and a binder moiety covalently linked to the graphite moiety. The binder moiety possesses a structure expressed as Formula (IV´). The modified graphite according to this disclosure solves the problem that the binder floats up during the preparation of the negative electrode plate of the secondary battery.

What is claimed is: 
     
         1 . A type of modified graphite, wherein the modified graphite comprises a graphite moiety and a binder moiety covalently linked to the graphite moiety, wherein the binder moiety possesses a structure expressed as Formula (IV´):
                     
 wherein, 
 R 1  to R 6  each are independently selected from hydrogen, halogen, cyano, hydroxyl, amino, substituent-free or substituent-containing C 1  to C 6  alkyl, substituent-free or substituent-containing C 1  to C 6  alkoxyl, substituent-free or substituent-containing C 2  to C 6  alkenyl, or substituent-free or substituent-containing C 6  to C 20  aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkenyl, and aryl each are at least one selected from C 1  to C 3  alkyl, hydroxyl, amino, amido, cyano, carboxyl, or halogen; 
 R 7  to R 9  each are independently selected from hydrogen, hydroxyl, amino, substituent-free or substituent-containing C 1  to C 6  alkyl, substituent-free or substituent-containing C 1  to C 6  alkoxyl, substituent-free or substituent-containing C 1  to C 6  alkylamino, substituent-free or substituent-containing C 2  to C 6  alkenyl, or substituent-free or substituent-containing C 6  to C 20  aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkylamino, alkenyl, and aryl each are at least one selected from hydroxyl, carboxyl, amino, amido, or halogen; 
 R 10  represents linear or branched C 1  to C 12  alkyl; 
 R 11  represents halogen or cyano; 
 Z is selected from linear or branched C 1  to C 5  alkylthio; 
 L represents linear or branched C 1  to C 12  alkylidene; 
 R 13a  represents #—COO—*, #—CH 2 O—*, or #—NH—*, and # represents a position linked to L, and * represents a position linked to the graphite moiety; and 
 a ratio of m to n is 1 to 100. 
 
     
     
         2 . The modified graphite according to  claim 1 , wherein m is an integer ranging from 500 to 15,000, and n is an integer ranging from 500 to 15,000. 
     
     
         3 . The modified graphite according to  claim 1 , wherein a number-average molecular weight of the binder moiety of Formula (IV´) is 30,000 to 3,000,000. 
     
     
         4 . The modified graphite according to  claim 1 , wherein structural units
                                             in the binder moiety are copolymerized in a random, blocked, and/or alternating manner, and optionally, in a blocked manner.   
     
     
         5 . The modified graphite according to  claim 1 , wherein the binder moiety is selected from the following structures:
                                                               wherein * represents a position at which the binder moiety is covalently linked to the graphite moiety.   
     
     
         6 . The modified graphite according to  claim 1 , wherein a mass ratio between the graphite moiety and the binder moiety is 85: 12 to 96.5: 0.5. 
     
     
         7 . The modified graphite according to  claim 6 , wherein a mass ratio between the graphite moiety and the binder moiety is 90: 7 to 96: 1. 
     
     
         8 . A negative electrode plate, wherein the negative electrode plate comprises a negative current collector and a negative material layer disposed on at least one surface of the negative current collector, and the negative material layer comprises the modified graphite according to  claim 1 . 
     
     
         9 . A secondary battery, wherein the secondary battery further comprises the negative electrode plate according to  claim 8 . 
     
     
         10 . A battery module, comprising the secondary battery according to  claim 9 . 
     
     
         11 . A battery pack, comprising at least one of the secondary battery according to  claim 9 . 
     
     
         12 . An electrical device, comprising at least one of the secondary battery according to  claim 9 . 
     
     
         13 . A preparation method of modified graphite, comprising:
 leaving a binder compound to react with graphite in a solvent in the presence of a catalyst, wherein   the binder compound possesses a structure expressed as Formula (IV):
                     
 wherein, 
   R 1  to R 6  each are independently selected from hydrogen, halogen, cyano, hydroxyl, amino, substituent-free or substituent-containing C 1  to C 6  alkyl, substituent-free or substituent-containing C 1  to C 6  alkoxyl, substituent-free or substituent-containing C 2  to C 6  alkenyl, or substituent-free or substituent-containing C 6  to C 20  aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkenyl, and aryl each are at least one selected from C 1  to C 3  alkyl, hydroxyl, amino, amido, cyano, carboxyl, or halogen;   R 7  to R 9  each are independently selected from hydrogen, hydroxyl, amino, substituent-free or substituent-containing C 1  to C 6  alkyl, substituent-free or substituent-containing C 1  to C 6  alkoxyl, substituent-free or substituent-containing C 1  to C 6  alkylamino, substituent-free or substituent-containing C 2  to C 6  alkenyl, or substituent-free or substituent-containing C 6  to C 20  aryl, wherein substituents in the substituent-containing alkyl, alkoxyl, alkylamino, alkenyl, and aryl each are at least one selected from hydroxyl, carboxyl, amino, amido, or halogen;   R 10  represents linear or branched C 1  to C 12  alkyl;   R 11  represents halogen or cyano;   Z is selected from linear or branched C 1  to Cs alkylthio;   L represents linear or branched C 1  to C 12  alkylidene;   R 13  represents carboxyl, hydroxymethyl, or amino; and   a ratio of m to n is 1 to 100.   
     
     
         14 . The preparation method according to  claim 13 , wherein, in the binder compound, m is an integer ranging from 500 to 15,000, and n is an integer ranging from 500 to 15,000. 
     
     
         15 . The preparation method according to  claim 13 , wherein a number-average molecular weight of the binder compound is 30,000 to 3,000,000. 
     
     
         16 . The preparation method according to  claim 13 , wherein structural units
                                             in the binder compound are copolymerized in a random, blocked, and/or alternating manne.   
     
     
         17 . The preparation method according to  claim 13 , wherein the binder compound is at least one selected from:
                                                                   .   
     
     
         18 . The preparation method according to  claim 13 , wherein a pH value of the reaction is 4 to 7. 
     
     
         19 . The preparation method according to  claim 13 , wherein a mass ratio between the graphite and the binder compound is 85: 12 to 96.5: 0.5. 
     
     
         20 . The preparation method according to  claim 13 , wherein the reaction occurs at 20° C. to 40° C.